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Merge pull request #692 from mcarton/format

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Lint about `format!("string lit")` with no argument
This commit is contained in:
llogiq 2016-02-21 03:16:41 +01:00
commit 9c36736f51
13 changed files with 206 additions and 59 deletions
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3
README.md
View file

@ -8,7 +8,7 @@ A collection of lints to catch common mistakes and improve your Rust code.
[Jump to usage instructions](#usage)
##Lints
There are 122 lints included in this crate:
There are 123 lints included in this crate:
name | default | meaning
---------------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
@ -126,6 +126,7 @@ name
[unused_lifetimes](https://github.com/Manishearth/rust-clippy/wiki#unused_lifetimes) | warn | unused lifetimes in function definitions
[use_debug](https://github.com/Manishearth/rust-clippy/wiki#use_debug) | allow | use `Debug`-based formatting
[used_underscore_binding](https://github.com/Manishearth/rust-clippy/wiki#used_underscore_binding) | warn | using a binding which is prefixed with an underscore
[useless_format](https://github.com/Manishearth/rust-clippy/wiki#useless_format) | warn | useless use of `format!`
[useless_transmute](https://github.com/Manishearth/rust-clippy/wiki#useless_transmute) | warn | transmutes that have the same to and from types
[useless_vec](https://github.com/Manishearth/rust-clippy/wiki#useless_vec) | warn | useless `vec!`
[while_let_loop](https://github.com/Manishearth/rust-clippy/wiki#while_let_loop) | warn | `loop { if let { ... } else break }` can be written as a `while let` loop

7
src/collapsible_if.rs
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@ -14,6 +14,7 @@
use rustc::lint::*;
use rustc_front::hir::*;
use std::borrow::Cow;
use syntax::codemap::Spanned;
use utils::{in_macro, snippet, snippet_block, span_lint_and_then};
@ -95,11 +96,11 @@ fn requires_brackets(e: &Expr) -> bool {
}
}
fn check_to_string(cx: &LateContext, e: &Expr) -> String {
fn check_to_string(cx: &LateContext, e: &Expr) -> Cow<'static, str> {
if requires_brackets(e) {
format!("({})", snippet(cx, e.span, ".."))
format!("({})", snippet(cx, e.span, "..")).into()
} else {
format!("{}", snippet(cx, e.span, ".."))
snippet(cx, e.span, "..")
}
}

112
src/format.rs Normal file
View file

@ -0,0 +1,112 @@
use rustc::front::map::Node::NodeItem;
use rustc::lint::*;
use rustc_front::hir::*;
use syntax::ast::LitKind;
use utils::{DISPLAY_FMT_METHOD_PATH, FMT_ARGUMENTS_NEWV1_PATH};
use utils::{is_expn_of, match_path, span_lint};
/// **What it does:** This lints about use of `format!("string literal with no argument")`.
///
/// **Why is this bad?** There is no point of doing that. If you want a `String` you can use
/// `to_owned` on the string literal. The even worse `&format!("foo")` is often encountered in the
/// wild.
///
/// **Known problems:** None.
///
/// **Example:** `format!("foo")`
declare_lint! {
pub USELESS_FORMAT,
Warn,
"useless use of `format!`"
}
#[derive(Copy, Clone, Debug)]
pub struct FormatMacLint;
impl LintPass for FormatMacLint {
fn get_lints(&self) -> LintArray {
lint_array![USELESS_FORMAT]
}
}
impl LateLintPass for FormatMacLint {
fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
if let Some(span) = is_expn_of(cx, expr.span, "format") {
match expr.node {
// `format!("{}", foo)` expansion
ExprCall(ref fun, ref args) => {
if_let_chain!{[
let ExprPath(_, ref path) = fun.node,
args.len() == 2,
match_path(path, &FMT_ARGUMENTS_NEWV1_PATH),
// ensure the format string is `"{..}"` with only one argument and no text
check_static_str(cx, &args[0]),
// ensure the format argument is `{}` ie. Display with no fancy option
check_arg_is_display(&args[1])
], {
span_lint(cx, USELESS_FORMAT, span, "useless use of `format!`");
}}
}
// `format!("foo")` expansion contains `match () { () => [], }`
ExprMatch(ref matchee, _, _) => {
if let ExprTup(ref tup) = matchee.node {
if tup.is_empty() {
span_lint(cx, USELESS_FORMAT, span, "useless use of `format!`");
}
}
}
_ => (),
}
}
}
}
/// Checks if the expressions matches
/// ```
/// { static __STATIC_FMTSTR: &[""] = _; __STATIC_FMTSTR }
/// ```
fn check_static_str(cx: &LateContext, expr: &Expr) -> bool {
if_let_chain! {[
let ExprBlock(ref block) = expr.node,
block.stmts.len() == 1,
let StmtDecl(ref decl, _) = block.stmts[0].node,
let DeclItem(ref decl) = decl.node,
let Some(NodeItem(decl)) = cx.tcx.map.find(decl.id),
decl.name.as_str() == "__STATIC_FMTSTR",
let ItemStatic(_, _, ref expr) = decl.node,
let ExprAddrOf(_, ref expr) = expr.node, // &[""]
let ExprVec(ref expr) = expr.node,
expr.len() == 1,
let ExprLit(ref lit) = expr[0].node,
let LitKind::Str(ref lit, _) = lit.node,
lit.is_empty()
], {
return true;
}}
false
}
/// Checks if the expressions matches
/// ```
/// &match (&42,) {
/// (__arg0,) => [::std::fmt::ArgumentV1::new(__arg0, ::std::fmt::Display::fmt)],
/// })
/// ```
fn check_arg_is_display(expr: &Expr) -> bool {
if_let_chain! {[
let ExprAddrOf(_, ref expr) = expr.node,
let ExprMatch(_, ref arms, _) = expr.node,
arms.len() == 1,
let ExprVec(ref exprs) = arms[0].body.node,
exprs.len() == 1,
let ExprCall(_, ref args) = exprs[0].node,
args.len() == 2,
let ExprPath(None, ref path) = args[1].node,
match_path(path, &DISPLAY_FMT_METHOD_PATH)
], {
return true;
}}
false
}

76
src/lib.rs
View file

@ -35,59 +35,63 @@ extern crate rustc_plugin;
use rustc_plugin::Registry;
pub mod consts;
#[macro_use]
pub mod utils;
pub mod copies;
pub mod consts;
pub mod types;
pub mod misc;
pub mod enum_glob_use;
pub mod eq_op;
pub mod bit_mask;
pub mod ptr_arg;
pub mod needless_bool;
// begin lints modules, do not remove this comment, it’s used in `update_lints`
pub mod approx_const;
pub mod eta_reduction;
pub mod array_indexing;
pub mod attrs;
pub mod bit_mask;
pub mod block_in_if_condition;
pub mod collapsible_if;
pub mod copies;
pub mod cyclomatic_complexity;
pub mod derive;
pub mod drop_ref;
pub mod entry;
pub mod enum_glob_use;
pub mod enum_variants;
pub mod eq_op;
pub mod escape;
pub mod eta_reduction;
pub mod format;
pub mod identity_op;
pub mod items_after_statements;
pub mod minmax;
pub mod mut_mut;
pub mod mut_reference;
pub mod len_zero;
pub mod attrs;
pub mod collapsible_if;
pub mod block_in_if_condition;
pub mod unicode;
pub mod shadow;
pub mod strings;
pub mod methods;
pub mod returns;
pub mod lifetimes;
pub mod loops;
pub mod ranges;
pub mod map_clone;
pub mod matches;
pub mod precedence;
pub mod methods;
pub mod minmax;
pub mod misc;
pub mod misc_early;
pub mod mut_mut;
pub mod mut_reference;
pub mod mutex_atomic;
pub mod zero_div_zero;
pub mod open_options;
pub mod needless_bool;
pub mod needless_features;
pub mod needless_update;
pub mod no_effect;
pub mod open_options;
pub mod panic;
pub mod precedence;
pub mod print;
pub mod ptr_arg;
pub mod ranges;
pub mod regex;
pub mod returns;
pub mod shadow;
pub mod strings;
pub mod temporary_assignment;
pub mod transmute;
pub mod cyclomatic_complexity;
pub mod escape;
pub mod entry;
pub mod misc_early;
pub mod array_indexing;
pub mod panic;
pub mod derive;
pub mod print;
pub mod types;
pub mod unicode;
pub mod vec;
pub mod drop_ref;
pub mod regex;
pub mod zero_div_zero;
// end lints modules, do not remove this comment, it’s used in `update_lints`
mod reexport {
pub use syntax::ast::{Name, NodeId};
@ -160,6 +164,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
reg.register_late_lint_pass(box types::AbsurdExtremeComparisons);
reg.register_late_lint_pass(box regex::RegexPass::default());
reg.register_late_lint_pass(box copies::CopyAndPaste);
reg.register_late_lint_pass(box format::FormatMacLint);
reg.register_lint_group("clippy_pedantic", vec![
enum_glob_use::ENUM_GLOB_USE,
@ -206,6 +211,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
eq_op::EQ_OP,
escape::BOXED_LOCAL,
eta_reduction::REDUNDANT_CLOSURE,
format::USELESS_FORMAT,
identity_op::IDENTITY_OP,
items_after_statements::ITEMS_AFTER_STATEMENTS,
len_zero::LEN_WITHOUT_IS_EMPTY,

10
src/loops.rs
View file

@ -245,13 +245,13 @@ impl LateLintPass for LoopsPass {
let mut other_stuff = block.stmts
.iter()
.skip(1)
.map(|stmt| format!("{}", snippet(cx, stmt.span, "..")))
.collect::<Vec<String>>();
.map(|stmt| snippet(cx, stmt.span, ".."))
.collect::<Vec<Cow<_>>>();
if inner_stmt_expr.is_some() {
// if we have a statement which has a match,
if let Some(ref expr) = block.expr {
// then collect the expression (without semicolon) below it
other_stuff.push(format!("{}", snippet(cx, expr.span, "..")));
other_stuff.push(snippet(cx, expr.span, ".."));
}
}
@ -317,8 +317,8 @@ impl LateLintPass for LoopsPass {
span_lint(cx,
UNUSED_COLLECT,
expr.span,
&format!("you are collect()ing an iterator and throwing away the result. Consider \
using an explicit for loop to exhaust the iterator"));
"you are collect()ing an iterator and throwing away the result. \
Consider using an explicit for loop to exhaust the iterator");
}
}
}

10
src/methods.rs
View file

@ -530,10 +530,10 @@ fn lint_or_fun_call(cx: &LateContext, expr: &Expr, name: &str, args: &[P<Expr>])
return;
}
let sugg = match (fn_has_arguments, !or_has_args) {
(true, _) => format!("|_| {}", snippet(cx, arg.span, "..")),
(false, false) => format!("|| {}", snippet(cx, arg.span, "..")),
(false, true) => format!("{}", snippet(cx, fun.span, "..")),
let sugg: Cow<_> = match (fn_has_arguments, !or_has_args) {
(true, _) => format!("|_| {}", snippet(cx, arg.span, "..")).into(),
(false, false) => format!("|| {}", snippet(cx, arg.span, "..")).into(),
(false, true) => snippet(cx, fun.span, ".."),
};
span_lint(cx, OR_FUN_CALL, span, &format!("use of `{}` followed by a function call", name))
@ -589,7 +589,7 @@ fn lint_extend(cx: &LateContext, expr: &Expr, args: &MethodArgs) {
span_lint(cx,
EXTEND_FROM_SLICE,
expr.span,
&format!("use of `extend` to extend a Vec by a slice"))
"use of `extend` to extend a Vec by a slice")
.span_suggestion(expr.span,
"try this",
format!("{}.extend_from_slice({}{})",

5
src/misc_early.rs
View file

@ -45,10 +45,7 @@ impl EarlyLintPass for MiscEarly {
fn check_pat(&mut self, cx: &EarlyContext, pat: &Pat) {
if let PatKind::Struct(ref npat, ref pfields, _) = pat.node {
let mut wilds = 0;
let type_name = match npat.segments.last() {
Some(elem) => format!("{}", elem.identifier.name),
None => String::new(),
};
let type_name = npat.segments.last().expect("A path must have at least one segment").identifier.name;
for field in pfields {
if field.node.pat.node == PatKind::Wild {

4
src/mut_reference.rs
View file

@ -39,13 +39,13 @@ impl LateLintPass for UnnecessaryMutPassed {
If this happened, the compiler would have \
aborted the compilation long ago");
if let ExprPath(_, ref path) = fn_expr.node {
check_arguments(cx, &arguments, function_type, &format!("{}", path));
check_arguments(cx, &arguments, function_type, &path.to_string());
}
}
ExprMethodCall(ref name, _, ref arguments) => {
let method_call = MethodCall::expr(e.id);
let method_type = borrowed_table.method_map.get(&method_call).expect("This should never happen.");
check_arguments(cx, &arguments, method_type.ty, &format!("{}", name.node.as_str()))
check_arguments(cx, &arguments, method_type.ty, &name.node.as_str())
}
_ => {}
}

4
src/regex.rs
View file

@ -105,7 +105,7 @@ impl LateLintPass for RegexPass {
Ok(r) => {
if let Some(repl) = is_trivial_regex(&r) {
span_help_and_lint(cx, TRIVIAL_REGEX, args[0].span,
&"trivial regex",
"trivial regex",
&format!("consider using {}", repl));
}
}
@ -123,7 +123,7 @@ impl LateLintPass for RegexPass {
Ok(r) => {
if let Some(repl) = is_trivial_regex(&r) {
span_help_and_lint(cx, TRIVIAL_REGEX, args[0].span,
&"trivial regex",
"trivial regex",
&format!("consider using {}", repl));
}
}

4
src/types.rs
View file

@ -491,12 +491,12 @@ fn check_type(cx: &LateContext, ty: &Ty) {
visitor.visit_ty(ty);
visitor.score
};
// println!("{:?} --> {}", ty, score);
if score > 250 {
span_lint(cx,
TYPE_COMPLEXITY,
ty.span,
&format!("very complex type used. Consider factoring parts into `type` definitions"));
"very complex type used. Consider factoring parts into `type` definitions");
}
}

2
src/utils/mod.rs
View file

@ -28,7 +28,9 @@ pub const CLONE_TRAIT_PATH: [&'static str; 2] = ["clone", "Clone"];
pub const COW_PATH: [&'static str; 3] = ["collections", "borrow", "Cow"];
pub const DEBUG_FMT_METHOD_PATH: [&'static str; 4] = ["std", "fmt", "Debug", "fmt"];
pub const DEFAULT_TRAIT_PATH: [&'static str; 3] = ["core", "default", "Default"];
pub const DISPLAY_FMT_METHOD_PATH: [&'static str; 4] = ["std", "fmt", "Display", "fmt"];
pub const DROP_PATH: [&'static str; 3] = ["core", "mem", "drop"];
pub const FMT_ARGUMENTS_NEWV1_PATH: [&'static str; 4] = ["std", "fmt", "Arguments", "new_v1"];
pub const FMT_ARGUMENTV1_NEW_PATH: [&'static str; 4] = ["std", "fmt", "ArgumentV1", "new"];
pub const HASHMAP_ENTRY_PATH: [&'static str; 5] = ["std", "collections", "hash", "map", "Entry"];
pub const HASHMAP_PATH: [&'static str; 5] = ["std", "collections", "hash", "map", "HashMap"];

15
tests/compile-fail/format.rs Executable file
View file

@ -0,0 +1,15 @@
#![feature(plugin)]
#![plugin(clippy)]
#![deny(useless_format)]
fn main() {
format!("foo"); //~ERROR useless use of `format!`
format!("{}", 42); //~ERROR useless use of `format!`
format!("{:?}", 42); // we only want to warn about `{}`
format!("{:+}", 42); // we only want to warn about `{}`
format!("foo {}", 42);
format!("{} bar", 42);
println!("foo");
println!("foo {}", 42);
}

13
util/update_lints.py
View file

@ -60,6 +60,13 @@ def gen_group(lints, levels=None):
yield ' %s::%s,\n' % (module, name.upper())
def gen_mods(lints):
"""Declare modules"""
for module in sorted(set(lint[0] for lint in lints)):
yield 'pub mod %s;\n' % module
def replace_region(fn, region_start, region_end, callback,
replace_start=True, write_back=True):
"""Replace a region in a file delimited by two lines matching regexes.
@ -128,6 +135,12 @@ def main(print_only=False, check=False):
lambda: ['There are %d lints included in this crate:\n' % len(lints)],
write_back=not check)
# update the `pub mod` list
changed |= replace_region(
'src/lib.rs', r'begin lints modules', r'end lints modules',
lambda: gen_mods(lints),
replace_start=False, write_back=not check)
# same for "clippy" lint collection
changed |= replace_region(
'src/lib.rs', r'reg.register_lint_group\("clippy"', r'\]\);',